Sheet interrupter

ABSTRACT

Sheet interrupter means for a sheet-fed printing press wherein upper and lower printing cylinders are supported by eccentric bearings permitting simultaneous actuation of the upper and lower cylinders between printing and &#39;&#39;&#39;&#39;off-impression&#39;&#39;&#39;&#39; positions. A throw-off cylinder actuates a series of links to rotate the eccentric bearings.

U I Unlted States Patent 11 1 1111 3,785,287 Dahlgren Jan. 15, 1974SHEET INTERRUPTER 3,527,165 9/1970 Harless .1 101 143 2,911,907 11/1959Davidson 101/137 [76] Invent Dahlgren, 726 Regal 3,477,367 11/1969Richards 101/137 Dallas, 75247 3,473,468 10/1969 Vandeman et a1 101/1373, Huck 1211 Appl' 249944 Primary Examiner-Robert E. Pulfrey Rd d U S Ali ti D Assistant ExaminerE. M. Coven [63] Continuation-impart of Ser.No. 737,521, June 17, Atmmey Howard Moore et 1968, Pat. No. 3,664,261.

. [57] ABSTRACT [52] US. Cl 101/247, 101/137, 101/184 [51] Int. Cl B41113/24 Sheet mtermpter means for a Sheet'fed prmtmg press 58 Field ofSearch 101/137 218 247 wherein "PPer and Priming cylinders are 101 /229ported by eccentricbearings permitting simultaneous actuation of theupper and lower cylinders between [56], References Cited printing andoff-impression positions. A throw-off 1 cylinder actuates a series oflinks to rotate the eccen- UNITED STATES PATENTS trig bearings.2,753,798 7/1956 Babst 101/232 3,664,261 5/l972 5 Claims, 34 DrawingFigures Dahlgren 101/177 PATENTEU JAN 1 5 I974 SHEET UHF 18 PMENIEUJM 15m4 SHIN 02 (1F 18 1 mm a Wkll.

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BACKGROUND OF THE INVENTION No significant advances have been madepresenting new concepts in sheet-fed printing systems for decades.Printing systems designed for the sheet-fed printer are basically thesame and allow printing on one side of the sheet at a time, requiringsheets to be turned over and rerouted through the press for single ormulti-color perfecting. Sheets are progressively and meticulouslytransferred in serpentine fashion about transfer and impressioncylinders and hopefully registered from one cylinder to another and fromone printing unit to another until finally they emerge as a printedproduct; Printing units must be synchronized for color register throughnumerous drive and idler gears and consequently presses are extremelycomplex, massive units which are very expensive to manufacture becauseof numerous transfer and printing cylinders and mechanisms relatedthereto.

One or two color sheet-fed perfectors have been developed heretofore.However, these machines were specifically designed for specific jobs,such as mass production of paperback books, and are totally unsuitablefor high speed production of four-color process printing on both sidesof the paper.

Heretofore no commercially successful sheet-fed press had the capabilityof printing on two sides of a sheet in as many as four colors by passingthe paper through the press one time.

It is the common and accepted practice in the printing industry to run asheet to be printed through the sheet-fed press a multiplicity of timesto attain multicolor printing on two sides of a sheet. After each passof the sheet through the press, the plates must be changed and the pressmade ready for the next pass to apply other colors or to print on theback of the sheet. It is readily apparent to those skilled in theprinting art that a considerable amount of time is spent makingsheet-fed presses ready to print and in attaining proper registry of thenumerous components of the press.

In a typical four-color one-side printing press a sheet delivered fromthe feeder is caught by the gripper bars of a first transfer cylinder.The sheet is folded around the transfer cylinder and carried to thegrippers on the first impression cylinder where the grippers of thetransfer cylinder release the paper and it is caught by the grippers ofthe impression cylinder. The grippers on the impression cylinder rotatethe paper into contact with the blanket cylinder where printing isaccomplished in one color on one side of the sheet. When the grippers onthe impression cylinder release the sheet, grippers on a second transfercylinder grasp the sheet, causing the printed surface to be in contactwith the transfer cylinder while it is rotated to the grippers of asecond impression cylinder. The grippers of the second transfer cylinderrelease the sheet as it is caught by the grippers of the secondimpression cylinder which rotates the sheet into contact with a secondblanket where a second color is applied to the same side of the sheet.Grippers on a third transfer roller catch the sheet as it is released bythe grippers of the second impression cylinder and the printed surfaceis again brought into contact with a transfer cylinder while it is beingdelivered to the grippers of a third impression cylinder. This processis continued until the sheet passes to delivery. When one side of thesheet is completed, the press is replated, the sheets are turned andre-fed through the press to print the other side of the sheet.

Virtually all sheet-fed printing presses heretofore developed have thecharacteristics of feeding the sheet serpentine fashion through thepress while the grippers associated with each cylinder catch the sheetas it is being released by the grippers of the previous cylinder.

One of the major problems encountered by the printing industry lies insynchronizing the various cylinders whereby the sheet will be graspedand released at the proper moment for maintaining registry between thecylinders of successive towers so that colors do not' overlap orseparate.

Chains have been used in the past with limited success to transfersheets from one printing station to another. However, grippers supportedby the chain were positively indexed to the printing station cylindersin an attempt to regain register which was periodically lost betweenprinting stations.

A chain has inherent limitations as a smooth transfer media becausechordal motion of the links limit smooth flow; linear deformation of thechain results from numerous pivot joints. Lubrication requirements atjoints, to help prevent wear, noise, shock and vibration, presentmaintenance problems.

The gripper and chain transfer media could not, by itself, register thesheet between printing stations, even with the chain travellingprecisely at cylinder speeds. As a compromise, grippers had to beloosely supported on the chain, moved from normal position, and indexedto printing station cylinders prior to actual sheet transfer at thecylinder. As soon as sheet transfer was accomplished and the gripperbecame separated from index with the cylinder, the gripper jumped orjerked back into its normal relation with the chain.

In the transfer system employed and disclosed herein, there is nocontact between tape directed gripper bars and the printing cylindersthereby eliminating shock, vibration, wear, noise, mis-register andother apparent problems accompanied by chain supported grippers beingindexed to cylinders. The printing cylinders are entirely independent ofthe sheet transfer mechanism and vice versa except for speedsynchronization of cylinder surface speed with that of the tape.

Another problem has been the offsetting of wet ink on transfer cylindersfrom the freshly printed surface on the paper and consequently back onto the next sheet that is passed through the press. Heretofore, presseswith a multiplicity of towers for applying more than one color of ink tothe sheet were driven by a common drive through a complex gear train orthrough long shafts which have inherent distortion thereby increasingthe problem of synchronizing components of the press thereby makingprecision registry more difficult.

Typical four-color one-side printing presses have an average of about 20cylinders including the plate cylinders, blanket cylinders, impressioncylinders, transfer cylinders and skeleton wheels.

1. In a sheet fed printing press, a feeder station; a delivery station;at least one cylinder support, including spaced side membersintermediate the feeder and delivery stations; a printing cylinderjournaled between the side members; an impression cylinder adjacent theprinting cylinder, at least one of said cylinders having a gap formedtherein; throw-off means secured to said printing cylinder and to saidimpression cylinder, said throw-off means being movably secured to theside members; means to rotate the said cylinders; means to apply ink tothe printing cylinder; flexible conveyors movably extending along eachside of the press from the feeder station to the delivery station;spaced elongated sheet engaging means extending between the conveyorsand movable from the feeder station to the delivery station, said sheetengaging means being adapted to engage a sheet at the feeder station andcontinuously convey same between the surfaces of the printing andimpression cylinders to the delivery station; means to secure the sheetengaging means to the flexible conveyors adjacent ends of the sheetengaging means; means to synchronize the rotation of the cylinders andthe sheet engaging means to cause the gap and the sheet engaging meansto be simultaneously moved into coinciding relationship relative to eachother as the cylinders rotate, the sheet engaging means being spaced toenter the gap and move between the printing and impression cylinders innon-engaging relationship therewith; and actuating means to move thethrow-off means to move the printing cylinder and the impressioncylinder toward and away from a sheet moved therebetween by said sheetengaging means.
 2. The combination called for in claim 1 wherein thethrow-off means comprises, upper and lower bearings having outersurfaces eccentric to walls of a bore extending therethrough, ends ofsaid printing cylinder and said impression cylinder being rotatablysupported in the bores; and wherein said actuating means comprises,means secured to each of said upper and lower bearings arranged torotate the bearings to move the printing and impression cylinders.
 3. Ina sheet fed printing press, a feeder station; a delivery station; atleast one cylinder support, including spaced side members intermediatethe feeder station and the delivery station; throw-off means movablysecured to each of said side frames; a printing cylinder rotatablyjournaled in said throw-off means; an impression cylinder rotatablyjournaled in said throw-off means adjacent the printing cylinder, atleast one of said cylinders having a gap formed therein and extendinglongitudinally thereof to allow passage of a gripper member between saidcylinders; means to apply ink to the printing cylinder; continuousflexible sheet transfer means movably extending from the feeder stationto the delivery station; means to drive the sheet transfer means at apreselected constant speed; gripper members carried by the sheettransfer means adapted to receive and grip the edge of the sheet at thefeeder station and continuously convey same to the delivery station;carrier guide means adjacent opposite sides of the press to direct thegripper meMbers along a substantially straight path between oppositeends of the press; power transmission means to rotate said cylinders ata preselected constant speed; synchronizing means secured to the powertransmission means and to the means to drive the sheet transfer means tocause the sheet transfer means and the printing cylinder to move in aselected unchanging speed relationship; and actuating means securedrelative to at least one of the side frames to actuate the throw-offmeans from an off-impression position to an on-impression positionwherein each of said printing cylinder and said impression cylinder ismoved to engage a sheet carried by said gripper members positionedbetween the printing cylinder and the impression cylinder.
 4. A methodof printing comprising the steps of: positioning the leading edge of asheet in a gripper element; moving the gripper element along asubstantially straight path toward, through and away from a plurality ofprinting stations whereby the sheet when passing between adjacentcylinders in each printing station is maintained substantially in linecontact with the cylinders; rotating first and second throw-offeccentric bearings having printing and impression cylinders mountedtherein such that printing and impression cylinders are simultaneouslymoved into engagement with opposite sides of the sheet; and disengagingthe leading edge of the sheet from the gripper element after the sheethas been moved through each of the printing stations.
 5. The method ofclaim 4 wherein the step of moving the gripper element comprises,rotating endless flexible conveyors having a gripper element extendingtherebetween; and with the addition of step of synchronizing movement ofthe conveyors with movement of surfaces of the printing and impressioncylinders.